(a) Technical Field
The present invention relates to a parking guidance method. More particularly, the present invention relates to a parking guidance method for a vehicle, which displays on a monitor a straight section (estimated parking space) determined based on a relative angle input by a driver and an estimated backward track calculated from a steering angle, thereby enhancing driver's convenience and safety in the event of back-in perpendicular parking.
(b) Background Art
In general, an advanced safety vehicle (ASV) refers to a vehicle to which a variety of high technologies are applied for the purpose of enhancing driver's convenience and reducing vehicle accidents and saving energy.
As one of the safety and convenience systems widely applied to the ASV, various kinds of parking assistant systems such as back-in parking monitoring systems have been developed and provided. Such parking assistant systems help a driver back-in park conveniently and avoid vehicle collisions that may be caused due to an unintended departure from an appropriate parking lane.
As a back-in parking monitoring system, an image pick-up device for a vehicle has been proposed to prevent an accidental collision, in which a camera is mounted on the rear of the vehicle to display an image of the rear of the vehicle on a monitor.
The image pick-up device comprises an image input unit (camera) taking an image of the rear of the vehicle and outputting an image signal, a display unit (monitor) receiving the image signal output from the image input unit and displaying the corresponding image on a screen, and a control unit controlling the image transmission from the image input unit to the display unit.
As such, prior art parking monitoring systems equipped with such an image pick-up device merely display an image taken by a monitoring camera mounted on the rear of the vehicle on a monitor.
Accordingly, it has many drawbacks. For example, drivers must look at the monitor continuously while parking. Especially, inexperienced drivers may oftentimes cause an accidental collision due to an unintended departure from an appropriate parking lane.
In order to solve such drawbacks, many attempts have been made. For example, Korean Patent Publication No. 2005-60896 discloses a parking monitoring system that estimates a backward track of a vehicle using signals output from a vehicle speed sensor and a steering angle sensor mounted on the vehicle, synthesizes the estimated backward track with an image taken by a camera, and displays the synthesized image on a monitor, thus allowing the driver to identify the estimated backward track on the monitor while parking.
Also, Japanese Patent Publication No. 2000-78566 discloses a parking assistant device in which a camera picks up an image of the rear of a vehicle and a display device displays an estimated driving track synthesized based on a steering angle of the vehicle.
In addition, Japanese Patent Publication No. 2003-11762 discloses a parking assistant device that displays an image picked up by a camera mounted on a vehicle on a screen, a guide line in parallel to a line in contact with an estimated locus when the vehicle is moved back at a maximum steering angle of a steering wheel.
Moreover, Korean Patent Publication No. 2004-38880 discloses a parking support device that reads an estimated track corresponding to an initial position of a vehicle to be parked from a memory and displays a parking operation guide on a monitor screen.
As described above, the conventional parking assistant systems displays an image of the rear of a vehicle to a driver using a cameral mounted on the rear of the vehicle so as to allow the driver to recognize an obstacle when the vehicle is moved backward. In addition to the image, the prior art systems displays an estimated backward track according to a steering angle operated by the driver so as to allow the driver to determine whether or not the vehicle collides with an obstacle and to estimate a moving direction of the vehicle.
FIG. 1 is a diagram illustrating a conventional method for predicting a backward track when a vehicle is moved backward. Referring to the figure, when a vehicle rotates with respect to a point O on an extension line from a rear wheel axle, an estimated backward track 11 can be obtained by calculating radius of gyration R which is defined as the distance between the point O and a central point C of the rear wheel axle.
The radius of gyration R can be calculated by the following equation if a current steering angle of the vehicle is given.R=I/tan φ
wherein I represents the distance between the front wheel axle and rear wheel axle, and φ represents a wheel angle, which can be calculated by ‘φ=steering ratio×steering angle’.
In a vehicle equipped with the conventional parking assistant systems, the estimated backward track 11 according to a steering angle merely shows on a monitor a moving direction of the vehicle to a predetermined distance. Thus, it can only provide a driver with a rough guidance for perpendicular parking; it can hardly provide accurate guidance.
Referring to FIG. 2A, if the moving direction of the vehicle at an initial stop position for a perpendicular parking is not that much different from the direction of a parking space 1, the estimated backward track 11 will work. Referring to FIG. 2B, however, if the moving direction of the vehicle is almost perpendicular to the direction of the parking space 1, a problem occurs; as the estimated backward track 11 shows only a moving direction up to a predetermined distance, it cannot provide accurate guidance throughout the perpendicular parking.
Moreover, different drivers stop their vehicles for perpendicular parking in different positions. Even a particular single driver can stop his or her vehicle in different positions. Taking the above into consideration and in view of the characteristics of wide angle cameras used as a rear view camera, the prior art methods and systems can hardly provide accurate guidance.
Furthermore, since both relative distance and angle of the vehicle to the parking space 1 are changed according to the initial stop position of the vehicle, the prior art methods and systems cannot provide an accurate track for entering the parking space 1 to the driver and the driver thus has to change the steering angle continuously according to the circumstances.
The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.